Lowest BMW X4 running costs from a fuel consumption point of view belong to the smallest diesel engine, the 2.0-litre 20d. With the standard six-speed manual gearbox it averages a claimed 50.4-54.3mpg (depending on which wheels are fitted) while with the optional eight-speed auto that figure actually improves slightly, to between 52.3 and 56.5mpg.

There’s little difference between the more powerful auto-only 3.0-litre 30d and 35d engines. The 30d manages between 46.3 and 49.6mpg and the 35d 47.1mpg.

All engines meet the new, tighter EU6 emissions legislation set by the European Union. Lowest BMW X4 emissions belong to the automatic 20d, which averages between 131 and 141g/km of CO2 depending on which wheels are fitted. Manual versions fare slightly worse at 136 to 146g/km.

The 30d is rated between 149 and 159g/km and the 35d at 157g/km.

If you want the lowest possible emissions, you can spec the X4 with more aerodynamically efficient 17-inch wheels with low-rolling resistance tyres. When fitted with those wheels 20d and 30d models emit 7g/km less CO2.

All engines feature stop/start and brake energy regeneration (which charges the battery only when the car is braking or otherwise decelerating – according to BMW this improves fuel efficiency by up to three percent).

The X4 is heavily based on the BMW X3 which thus far has proved satisfactorily reliable. We’d therefore suggest that BMW X4 reliability shouldn’t cause too much cause for concern. The engine fitted to the 20d is a new design but most other components are a known quantity.